The present application claims priority to German Application No. DE 10039049.8 filed Aug. 10, 2000, the entire contents of which are incorporated herein by refeference.
1. Field of the Invention
The invention provides nucleotide sequences from Coryneform bacteria which code for the lysR3 gene and a process for the fermentative preparation of amino acids, in particular L-lysine and L-valine, by attenuation of the lysR3 gene. The lysR3 gene codes for the LysR3 protein, which is a transcription regulator of the LysR family.
2. Discussion of the Background
L-Amino acids, in particular L-lysine and L-valine, are used in human medicine and in the pharmaceuticals industry, in the foodstuffs industry and very particularly in animal nutrition.
It is known that amino acids are prepared by fermentation from strains of Coryneform bacteria, in particular Corynebacterium glutamicum. Because of their great importance, work is constantly being undertaken to improve the preparation processes. Improvements to the process can relate to fermentation measures, such as, for example, stirring and supply of oxygen, or the composition of the nutrient media, such as, for example, the sugar concentration during the fermentation, or the working up to the product form by, for example, ion exchange chromatography, or the intrinsic output properties of the microorganism itself.
Methods of mutagenesis, selection and mutant selection are used to improve the output properties of these microorganisms. Strains which are resistant to antimetabolites or are auxotrophic for metabolites of regulatory importance and which produce amino acids are obtained in this manner.
Methods of the recombinant DNA technique have also been employed for some years for improving the strain of Corynebacterium strains which produce L-amino acids.
However, there remains a critical need for improved methods of producing L-amino acids and thus for the provision of strains of bacteria producing higher amounts of L-amino acids. On a commercial or industrial scale even small improvements in the yield of L-amino acids, or the efficiency of their production, are economically significant. Prior to the present invention, it was not recognized that attenuation of lysR3 gene encoding the a LysR3 transcriptional regulation protein would improve L-amino acid yields.
One object of the present invention, is providing a new process adjuvant for improving the fermentative production of L-amino acids, particularly L-lysine and L-glutamate. Such process adjuvants include enhanced bacteria, preferably enhanced Coryneform bacteria which express attenuated amounts of LysR3 transcriptional regulator which is encoded by the lysR3 gene.
Thus, another object of the present invention is providing such an bacterium, which expresses an attenuated amount of LysR3 transcriptional regulator or gene products of the lysR3 gene.
Another object of the present invention is providing a bacterium, preferably a Coryneform bacterium, which expresses a polypeptide that has an attenuated LysR3 transcriptional regulator activity. Another object of the invention is to provide a nucleotide sequence encoding a polypeptide which has LysR3 transcriptional regulator sequence. One embodiment of such a sequence is the nucleotide sequence of SEQ ID NO: 1.
A further object of the invention is a method of making LysR3 transcriptional regulator or an isolated polypeptide having a LysR3 transcriptional regulator activity, as well as use of such isolated polypeptides in the production of amino acids. One embodiment of such a polypeptide is the polypeptide having the amino acid sequence of SEQ ID NO: 2.
Other objects of the invention include methods of detecting nucleic acid sequences homologous to SEQ ID NO: 1, particularly nucleic acid sequences encoding polypeptides that have LysR3 transcriptional regulator activity, and methods of making nucleic acids encoding such polypeptides.
The above objects highlight certain aspects of the invention. Additional objects, aspects and embodiments of the invention are found in the following detailed description of the invention.